How far does light pollution reach?

Installation of the autonomous MiNiO in front of the Qaleraliq glacier. Credit: D. Padrón. 

Between 27th August and 7th September the Shelios 2023 expedition tool a group of researchers and students at the south of Iceland and Greenland, where they set up two experiments to measure the natural darkness of the arctic night, and from where they broadcast the aurora borealis. Among the apparatus they installed is the autonomous MiNiO (Meteo Nano Observatory) controller, developed by the Technological Institute for Renewable Energies (ITER), for the Interreg EELabs project, coordinated by the Instituto de Astrofísica de Canarias (IAC).

As well as making people aware of the problems of light pollution, and amplifying the legislation with respect to the sky and night time ecosystems, the main aim of the Interreg EELabs project is to set up instrumentation to measure the natural darkness of the night sky. During the past three years a number of technological developments have been made, with this aim in mind. Among them are the MiNiO (Meteo Nano Observatory) controllers.

These devices complement the working of the laboratories because as well as being equipped with an SG-WAS photometer to measure the brightness of the night sky, they also include a surveying system comprising a forward looking camera and a camera pointing at the zenith, which permit the analysis of the surroundings and the sky respectively. In some of these installations they also include a thermographic sensor to analyze the temperature of the environment, and to detect moving objects, even in complete darkness.

Given the need to install MiNiOs in natural surroundings, without electricity supply, a system has been developed to give them energy autonomy, using the available sunlight. This system comprises a modular structure with a photovoltaic solar panel, a system which accumulates charge, and a source of intelligent electricity supply (SPS) which permits the apparatus to be run continuously. This allows them to be set up and to send their data from place with difficult access.

After testing the prototypes at the Teide Observatory (Tenerife) to analyze their behavior under valid operational conditions, they have been installed progressively n different sites. The process of improvement and development has, nevertheless continued.

At the present time there are three which are working. The first, sited in the Rambleta (upper building of the Tenerife Cable Car) has been used as a test bench because it is in extreme conditions of temperature and connectivity due to its altitude (some 3500 m). The results, when analyzed have helped to improve the next installations, at the Pico do Arieiro in Madeira (Portugal), and opposite the Qaleraliq Glacier (in the south of Greenland). The following one will be set up on the Island of Corvo, in the Azorez (Portugal), and will give LoRa coverture to the photmeters of the Caldeirao.

The Aurora Borealis from Greenland

During recent months there has been an increase in solar activity because our nearest star is reaching the mid point of its 25th magnetic cycle. The Sun is a ball of gas (plasma) which is in fusion reaction at its center, and electrically charged. The motion if this plasma generates a powerful magnetic field which changes polarity approximately every 11 years, producing what are known as solar cycles. After a period of low activity we observe how the number of sunspots and prominences increases, which during the coming months and years will produce an increase in the polar auroras.

“We have returned to Greenland during the new solar maximum, which is proving more active than expected. This is our third maximum at the glaciers in the south of Greenland. We were here in the years 2000 and 2015 when we could already note the recessing of the Qaleraliq glacier, one of the largest opposite the south of Greenland. This year, as well as installing a network of photometers and sky cameras, we have observed directly the evolution of the arctic ice”, comments Miquel Serra-Ricart, coordinator of the EELabs project and head of the Shelios 2023 expedition.

When the solar wind, highly energetic particles which are emitted by the solar corona, reach the magnetic field of the Earth, this guides them towards the poles, producing what are known as the Aurora Borealis if the particles enter towards the North Pole, or the Aurora Australis if they enter near the South Pole. The aurorae form in the Earth’s upper atmosphere and we see them as luminous curtains, with colours which go from green to red. This change of colour is due to the electrons from the solar wind colliding with atoms of oxygen (green tones) or molecules of nitrogen (red tones). During the Shelios 2023 expedition the team could send a broadcast of this phenomenon from the Fletanes camp opposite the Qaleraliq glacier. This broadcast was part of the outreach activities of the Interreg EELabs project.

Link to the broadcast: https://youtu.be/AdLKZKo15-o

The route of the Stars

Created in 2004 with the aim of promoting scientific vocations among the students at institutes and other educational centers, the Route of the Stars has, for yet another year, taken a group of students, this time to the south of Iceland and Greenland. This expedition put the final touch to a process which started years ago, and which the participants have declared was “an unforgettable experience”.

EELabs (eelabs.eu) is a project funded by the Programme INTERREG V-A MAC 2014-2020 and co-financed by FEDER (European Fund for Regional Development of the European Union, under contract number MAC2/4.6d/238. 5 centres in Macaronesia (IAC, UPGC, SPEA-Azores, SPEA-Madeira) work in EELabs. Its objective is to create laboratories to measure the energy efficiency of the artificial night-time illumination in the natural protected areas of Macaronesia (the Canaries, Madeira, and the Azores).

Auroras images obtained in 2023: https://flic.kr/s/aHBqjAUE1c 

Retreat of the Qaleraliq glacier front (South Greenland): https://flic.kr/p/2p9BAXu